This application is based on Japanese Patent Application No. 10-53482, filed Mar. 5, 1998, the content of which is cited herein by reference.
The present invention relates to an optical fiber seal verifying system used to probate an optical fiber seal.
In nuclear facilities, to comply with the NTP safeguards agreement based on the NTP (Nuclear Nonproliferation Treaty), many seals are used for the purpose of checking whether nuclear substances are illicitly taken out from storage facilities or casks. Judging whether seals have been tampered with is called "verification".
There are seals of various types, and currently, E type metal cap seals are widely used. However, as the first problem, the E type metal cap seals must be detached for verification to check the presence/absence of abnormalities. As the second problem, one to two weeks are required for verification.
To solve these problems, an optical fiber seal (also called a COBRA seal) has been developed by Sandia National Laboratories in USA.
The optical pattern of optical fiber transmission light on the seal end face is photographed in sealing and verification, and the two photographs are visually compared, thereby verifying an optical fiber seal.
By comparing the optical pattern photographed in sealing with the optical pattern photographed in verification, the presence/absence of seal break is determined. To do this, the optical patterns are recorded by photographing them, and the optical pattern in sealing and that in verification are visually compared and collated.
In this method, however, the load on the person who performs verification is heavy. In addition, the determination result cannot be quantified and contains the subjective point of view of the inspector.